Ore-treating process



Patented it 19235..

islets E i e ORE-TREATING 1 30431351:

No Drawing.

T 0 all whom it may concern:

. Be it known that I, FRANK M. Darrow, a citizen of the United States, residing at Jackson, county of Amador, State of California, have invented certain new and useful Improvements in Ore-Treating Processes, and l do declare the following to be a full, clear, and exact description of same This invention relates to improvements in ore-treating processes of a hydro-metallurgical nature, and particularly to a process for treating certain gold and silver ores which contain elements that prevent the precious metals from being extracted, removed .or successfully recovered from the ores by the ordinary cyaniding treatments or processes.

The steps usually taken in carrying out these ordinary processes are well known and need not be set forth here. Mostores yield readily to such treatments, but occasionally on ore is found which contains one or more elements of such nature that they act to prevent the effectual solution of the precious metals. This behavior is manifested mainly by those ores which contain graphite-schists or other metamorphosed carbonaceous matter. Frequently, when such ores are treated by the ordinary cyaniding methods, the solution when withdrawn contains such a small percentage of the precious metals as to render cyaniding unprofitable.

Several methods have ben tried out on these ores, but they all, as far as I am aware, are defective, in that they incur too much expense or fail to recover a sufficient percentage of the desirable precious metals.

The principal object of my invention therefore is to provide an ore-treatment process for ores of the above mentioned character, by means of which their detrimental qualities may be successfully and economically overcome, permitting a suiiicient extraction and recovery of the precious metals when cyanide solution is applied there to. Concentrates, tailings, or any other gold and silver bearing materials of the above named character that do not yield readily to ordinary cyanidation, may be treated by my process, and cyanided successfully and economically and a good recovery of the precious metals obtained.

In general, my process consists in mixing into the ores, which will usually be then in a wet pulped condition, a small amount of Application filed. November 22, 1922. Serial No. 602,634.

two reagents; cyanide solution is applied in the ordinary way and a good extraction of the precious metals obtained.

Each one of the necessary two reagents possess a different property or properties, and each reagent functions in a different way to bring about the desired results. The required two reagents used in my process are one, called in this specification a coating reagent, consisting of one or more substances of an oily, fatty, waxy, greasy, unctuous or similar oleaginous nature, almost insoluble in water, and another necessary reagent, called in this specification a modifying reagent consisting of one or more fairly soluble or easily miscible substances, such as certain soluble salts, some soaps, or other substances with similar properties to be more fully hereinafter described.

In practice, these two reagents may be fed one at a time. simultaneously, or mixed together and fed to the ore-pulp; either along with the cyanide or before the addition of the cyanide. Also the pulp may be kept either basic, neutral or acid. All these points and certain other details must be determined in practice by the special requirements of each individual ore under treatment. Likewise the amount of reagents required and the time of treatment necessary may vary when applied to different ores. However, in this process, it is essential that the two reagents be present together in the ore pulp, both at the same time, to mingle therewith and react together in and on the ore-pulp to bring about the desired beneficial effect.

To illustrate and described in more detail the cooperate functioning of these two reagents, take for instance, one case where an oil is used as the coating reagent; alon with which in the ore-pulp a soluble soap in this case, is added as'the modifyin reagent. Some of the well known properl ties of aqueous soap solutions are utilized; namely, that of assisting in emulsifying oils into the bulk liquid, so as, in this process, to distribute the oily substance and render it available in a fine state of division throughout the ore-pulp. Besides thus modifying the physical properties of the oily substance, the soap, when dissolved in the bulk liquid phase of the ore-pulp, also tends to modify the interfacial surface tensions at the surfaces f e solid par icles contained therein, so as to give the carbonaceous matter a greater preferential aflinity for the emulsilied oil or coating reagent. Part of the dissolved soap dissociates into its basic and acid constituents, and the so-liberated fattyacid component of high molecular weight, is strongly adsorbed in the pores and the surface of the contained graphitic or carbonaceous particles; there it forms a film onto which the oil particles cling and aggregate by adhesion and adsorption, so as to smear or coat over the surfaces and stop up the pores of the contained particles of carbonaceous or graphitic matter. Thus, througa the combined use of the above men tioned two reagents, the deleterious matter, whether carbonaceous, graphi'tic or otherwise, as the case may be, is elfectively given an insoluble protective coating or skin, which insulates it from the surrounding liquid and renders it inert during the extraction of the precious metals by cyanide.

The value of this process may be shown by citing an instance where it was used on carbonaceous gold ore from a well known mother lode gold mine. Into this ore, when in the wet pulped condition, had been added the coating reagent to an amount of 0.4 of a pound per ton of ore. The coating reagent used in this case was an oil, consisting mostly of a mixture of four parts of potroleum liquid paraffines, two parts of creosotes, and one part of pyridene. An aqueous solution of equal parts of the sodium salts of myristic, steric, and lauric acids was used as the modifying reagent this was added at the rate of 3 pounds per ton of ore. The whole was then mixed and pro-treated together, for ten minutes. After that the alkali and the weak solution of cyanide were added and allowed to remain in contact with the ore for 6 hours. When the solution was withdrawn from the ore, 78% of the gold content was extracted.

For further information and comparison, two samples of the same carbonaceous gold ore as used in the above test, were taken and treated separately. Into one sample was added only coating reagent, and into the o her was added only modifying reagent. hall and cyanide were added to each, and all conditions of treatment kept the same throughout the tests as in the one above, except that the two were kept separate. il' hen the solutions were withdrawn from each, only of the gold was extracted from the sample in which coating reagent alone was used, and only was extracted from the sample in which only modifying reagent was used; yet as shown above, 78% was successfully extracted when the two reagents were used together on the same portion of ore to mutually supply each others lack.

The necessity of using the two reagents together, and the usefulness and the novelty of this invention are shown by the above tests.

While this specification sets forth in detail the present or preferred steps of the process. still, in practice such deviations from such detail may be resorted to as not to form a departure from the spirit of the invention as delined by the appended claim. ilaving thus described my invention, what i claim as new and useful and desire to secure by Letters Patent, is:

The process of treating carbonaceous gold and silver ores consisting of treating the ores during or after crushing with an oleaginous substance and also a soapy substance, and extracting the precious metals by cyanide.

FRANK M. DAR-ROW. 

